In industrial scale reactions for hydrocarbon to olefin conversion, the desired products are typically lighter olefins such as ethylene and propylene. During these industrial processes, it is also desirable to achieve nearly complete conversion of the oxygenate feedstock to olefins. Many of the factors, however, that enhance the overall conversion rate of the reaction also reduce the selectivity of the reaction for production of lighter olefins, and vice versa.
U.S. Pat. No. 6,166,282 B1 discloses a process for converting oxygenates to olefins in a reactor with two reaction zones. Feedstock is introduced into a lower, dense phase zone from a single inlet to effect a partial conversion to light olefins. The dense phase zone includes a fluidized catalyst bed. It is disclosed that as the feedstock continues to move up in the reactor, it moves into a transition zone above the dense phase zone where the reaction continues essentially to completion. The dense phase zone operates at a superficial velocity of less than 1 meter per second, and the transition zone operates at a superficial velocity of from 1 to 4 meters per second.
What is needed are additional methods to improve the effectiveness of oxygenate to olefin reactors as well as other fluidized bed reactors. In particular, methods are needed to allow for introduction of feedstock through the sidewalls of a reactor. Such systems are particularly desirable in maintaining high selectivity to ethylene and propylene products while maximizing reactivity during oxygenate to olefin reactions.